1. Technical Field
The embodiments herein generally relate to weapons systems, and, more particularly, to equipment used for protection against the exhaust gases of missile launching systems.
2. Description of the Related Art
A vertical launching system (VLS) consists of a number of cells for holding and firing missiles on surface ships and submarines used by many navies around the world. Typically, each cell can hold a number of different types of missiles, enabling the ship flexibility to load an appropriate set for a given mission and to enable replacement of earlier missiles with upgrades without expensive rework. When the command is given, the missile flies straight up long enough to clear the cell and the ship, and then turns on course. The most popular VLS system in the world is the MK 41, being used by eleven navies around the world. The United States Navy will employ the MK 57 VLS on the U.S.S. Zumwalt class destroyers.
Both MK 41 and MK 57 VLS missile launchers primarily are configured as a plenum and uptake type gas management system. A plenum is a pressurized chamber holding fluids, and the uptake refers to the general upwards/vertical venting of pressurized gas from the plenum. These systems manage gases during a normal missile launch and also during retrained firing. However, a typical plenum and uptake approach results in substantial structural wear caused by normal missile launches, which decreases the ability to withstand a restrained firing, thus, limiting the number of missiles that can be launched prior to gas management system refurbishment.
The MK 41 and MK 57 VLS gas management system plenums protect their plenum floors with ablative material. Additional protection is provided underneath the rocket motor by using a bi-layer ablative material stack. The material on top of the stack is exposed to the rocket motor plume during normal missile fly outs, and the material on the bottom of the stack is exposed only during a missile restrained firing. However, the material is generally inadequate to prevent burn-through when exposed to plume jetting and long burn times because the ablative material, which tends to be expensive, typically do not have sufficient mechanical strength to resist the forces produced by the plume impingement.
The Mk 41 VLS gas management system also uses an aft closure, grid, and sill. The aft closure is a square multi-material, multilayer plate that has diagonal scores that allow it to “blow open” during a rocket motor firing. The sill keeps the aft closure from opening too far and the grid prevents the adjacent aft closures from opening in the opposite direction. However, this type of system requires a substantial number of components, the aft closure layup uses many different materials and a very process-intensive assembly, and the sill and grid are relatively difficult to manufacture and assemble. Moreover, this system is not readily adaptable for use on a general plenum box assemblies because it requires more space above the top of the plenum and more intrusion into the inside of the plenum.